Field of the Invention
The invention relates to holding an optical fiber of an optical fiber cable within an optical connector.
U.S. Pat. No. 5,080,460 discloses an optical fiber connector and is assigned to the assignee of the present invention. The connector of the '460 patent includes a compactable insert within a passage of an alignment ferrule for radially positioning an optical fiber extending therethrough relative the alignment ferrule. A plunger is force fit into the passage, compacting the insert into a constriction and causing the insert to concentrically grip the optical fiber.
The concentric gripping occurs because the ends of the insert are being compacted between the constriction and the plunger which would tend to bulge the middle of the insert. However, the insert is within the passage and constrained from bulging by the ferrule resulting in the insert collapsing upon, and concentrically gripping, the optical fiber. Compaction beyond initial engagement with the optical fiber produces stored energy within the insert. As the amount of compaction increases so does the amount of stored energy.
The stored energy causes the insert to continually exert an expansionary force in all directions. While some stored energy is helpful to maintain engagement with the optical fiber over time, excessive expansionary force may distort the front portion of the ferrule corresponding to the insert or allow the grip on the fiber to be lost by dislodging the plunger from its engagement with the ferrule.
The stored energy may be accommodated by over-designing the associated components. Stronger materials may be used or, where possible, the associated dimensions may be increased. These accommodations have trade-offs, for example, stronger materials may also be more difficult to form and additional material may add additional cost.
As the use of optical fiber connectors increases, it is necessary to provide more optimally designed connectors. Optimization of the type of connector disclosed in the '460 patent requires an insert capable of gripping the optical fiber concentrically while storing enough energy to accommodate dimensional fluctuations. However, the stored energy must be controlled so that it does not exert excessive expansionary force on the adjacent components. Although possible, it would be impractical to control the amount of energy stored within an insert of an assembled connector by tightly controlling the tolerances of the mating components. What is needed is an insert manufactured to limit expansionary force while still providing radial alignment and concentric gripping of the optical fiber.